Search

I've been thinking about building an aeroponic system from scratch for a while, and this week I gave it a first attempt.

The garden has been largely dominated by the massive eggplant lately. The eggplant itself is quite healthy, but it's a bad neighbor to everything else in the TurboGarden. It's simultaneously crowding it's neighbors and shading them under it's large canopy.

As far as I've researched, nobody is producing a single-site aeroponic unit. I thought it was time to make one.

I spend a long time thinking about how to assemble an aeroponic unit from scratch... I came to a few basic parts that would be necessary, then expanded on the idea:

A reservoir is needed for the water. The reservoir should be some type of opaque material, to prevent algae growth. Ideally, the reservoir should be easy to monitor and service.

In order to be an aeroponic system, you need to have sprayers. These sprayers need to take water from the reservoir and deliver it to the roots of the plant.

The plant needs to be supported, and it needs to be kept safe from damage during water changes and maintenance.

I started looking for my reservoir first. I considered lots of containers, from the simple Home Depot bucket to more exotic containers. I ended up choosing a dog-food container. Take a look at the photo below, and I'll start to explain why I decided on it.

I found a 40-pound size Vittles Vault, made by Gamma Plastics. It's intended to be an air-tight container for pet foods, but I had other ideas in mind. I liked the large water-tight door, the generous capacity for water, and the flat top of the container. It's naturally good at holding water, and is not prone to leaks.

You're probably noticing that there's a bucket on top... That's intentional. I decided to separate the reservoir from the plant's "chamber". The bucket has been fitted to hold a 6" net pot. The plant lives entirely in the bucket. Since the reservoir can be seperated from the bucket easily, I can clean the reservoir without disturbing the delicate roots.

How are they connected? Well, I wanted to make a system with as few points of failure as possible. Water likes to obey gravity, so in the chance of total failure, the water can fall safely back into the reservoir. It's the path of least resistance.

The bucket has a hole drilled through the bottom. The reservoir has a matching hole drilled through the top. Take a look, and it will make more sense:

That's actually a "through-hull" fitting, it's used in boating. It's a sealed "pass through" that leads directly down into the reservoir. This serves as our water-return. The holes in both the reservoir and the bucket were drawn using a simple compass, and were rough-cut using a Dremel tool. They were then sanded using a small drum-sander to achieve proper size and roundness.

Once the unit was dry-fit properly, I sealed the "through-hull" fitting with aquarium sealant, to ensure that it was totally water-tight.

The lid of the bucket has been cut to accommodate a large (6") net pot. The lid supports the weight of the plant, and the roots are able to hang freely inside the bucket. Here's a top view of the bucket's lit (and pot) for perspective:

Before we continue with construction, let's stop and talk about aeroponics for a moment. Aeroponics describes a special breed of hydroponics, where the roots of a plant are sprayed with an aerated nutrient solution. To make a spray, we force water through small jets. Luckily, these jets are pretty easy to obtain. I bought a handful of them at my local hydroponics shop. In case you don't have access quite as readily as I do, here's a link where you can buy them (please note, I have not done business with this merchant, and as such, cannot make any promises).

The small microjets are threaded, and usually screwed directly into PVC fittings of your choosing. Since nobody online seemed to know quite what size they are, here's the final answer: The microjets are threaded to fit a 10-32 machine thread hole. It's easy to make them fit into PVC. Simply drill a hole of appropriate size, then cut the threads with a 10-32 tap. 10-32 is a standard size (it's the fine-thread version of a #10 machine screw). You should be able to buy a 10-32 tap quite inexpensively at nearly any hardware store. Personally, I really like the Craftsman TapDriver. It's a screwdriver-shaped handle that stores taps internally. It's very convenient. Sadly, Sears does not have a good photo on the website, so I've got no link to share.

You're able to construct the supply lines for the microjets by simply using 1/2" PVC and fittings. It's easy to cut and glue PVC, and it doesn't require a lot of special tools.

Now that we know how we intend to supply the water; we need to know how we're going to get it there... We need a pump.

Here's an important advisory for you about pumps. Don't just think you can buy an off-the-shelf aquarium pump. I tried that. It didn't work.

Although these pumps look convenient, they lack sufficient power to make the jets work. A crappy pump will make your jets "dribble". You'll need a proper pump to get them to the critical pressure.

After some searching and testing, I wholeheartedly recommend an ActiveAqua PU250. The ActiveAqua brand is represented by Hydrofarm, and their pumps are just what you need. Shockingly, the ActiveAqua pump actually cost me less than the far-inferior pet-store variety.

Speaking of pumps, the ActiveAqua PU 250 (and larger) pumps offer an important and convenient feature. They have a pipe-thread connection to the pump. Many brands of pump simply have a tubing "slip fit" connection. I don't like "slip fit". It's not strong, and it's not reliable. Threaded connections are much stronger, and they'll make your life a lot easier. In this case, the PU250 has a 1/2" pipe thread connection for the "outbound" water. Here's a photo with the thread visible:

Ok... Now we've got all the ingredients together... Let's make it work.

I wanted as simple a connection as possible, so I got an idea early in the project: If I made the "return hole" in the bucket large enough, I could pass the supply line for the jets through the middle of it (meaning that I only have one hole to worry about instead of two). This leads me to my sprayer system.

It's a very simple setup. The pump shoots the water straight up a length of PVC pipe. This pipe is capped at the top, and the only way for the water to escape is through three microjets at the top. Here's a closeup of the jets at the top of the pipe:

The cap is just a regular 1/2" PVC cap. It's been drilled and threaded for three 10-32 sprayers, which screw into it nicely. The PVC cap is solvent-wended to the pipe to prevent leaks.

The pump rests inside the reservoir, with the sprayer-pipe extending vertically. The sprayer-pipe travels through the large "through-hull" fitting that connect the bucket and reservoir, and stops just below the plant's basket. Here's a photo of the whole thing assembled:

Also, just so you can see it from the top, here's another angle:

I like this design a lot, as it's pretty simple. The water shoots out of the sprayers, and is carried back to the reservoir by gravity. The pump is always sitting in water. The whole system is designed to be as leak-resistant as possible, while allowing for easy cleaning.

The big "door" on the reservoir allows for easy access when you're testing and adjusting your water. Additionally, you can completely disconnect the bucket from the reservoir, should you want to do more extensive cleaning. Since the plant never leaves the bucket, it's always shielded from damage and accidents.

The last part of the project was allowing the pump's cord to exit the reservoir. I put the hole both as high as possible and as far from the the "return" as possible, to minimize leak concerns. It's pretty simple. I drilled a 1" hole through the reservoir using a hole-saw, and fitted it with a large electrical grommet for a finished look.

Here's a rough estimate of the costs involved in building this aeroponic system:

Small bucket and lid, $4

Gamma Vittles Vault, $35

ActiveAqua PU250 Pump, $15

1 1/2" through-hull fitting, $7

Microjets, $2

6" net pot, $1

PVC pipe and fittings, $3

Total materials cost: Roughly $67. That's not bad, based on the costs of commercial units. I bought all the parts for this project locally,. The bucket and PVC were from Home Depot. The through-hull fitting was from a boating store. The pump, microjets, and net pot came from my local hydroponics shop. The Vittles Vault came from Petco.

You could certainly lower the cost by replacing the expensive Vittles Vault. Honestly, I just loved the easy access of the big watertight door, and was willing to incur the expense for a nicer maintenance experience in the future.

Admittedly, this was an experiment to build a "large plant, single site" unit. In my next experiment, I'll be looking at building a unit meant for several smaller (strawberry) plants. If you have comments or questions about how this was constructed, just let me know. If you have an improvement on the design, make sure to share it with the group.

On to the weekly writeup:

Bambino eggplants are tasty. I'm planning on growing several plants during the next grow cycle (that's a big part of why I built the new aeroponic system). The eggplants are appearing regularly.

Additionally, small strawberries are appearing all over the place. Thus far, we've eaten two of them, but they were early bloomers. The majority of them are just growing now.

We've started some new seeds. This time, it's Black Beauty eggplants and more of the Alexandria Alpine strawberries. Once the existing Bambino eggplant finishes it's lifecycle, I'll replace it (and the remaining sites) with baby strawberry plants. The new eggplants are destined for the newly constructed aeroponic system (and for Jessawick's secret Christmas present, another hydro system).

I'd like to start this week by posting a correction regarding some of my previous comments...

Last week, I expressed puzzlement regarding our eggplant fruits, and why they weren't growing any larger. Now I know better. The Bambino Baby Eggplant is only expected to grow to a diameter of approximately 1.5". Our little guys are fully mature, and nothing is wrong.

Actually, I'm very much looking forward to cooking the little Bambinos. I'm thinking that I can skewer them whole, and grill an entire bunch of them on a kabob. In theory, if they cook with the skin on, they should retain all their moisture.

Here's a photo of the first (and largest) of the Bambinos. It's the same one featured in previous posts:

We're planning some new experiments in the near future. I've started to purchase the items to construct an aeroponic unit from scratch. Thus far, we've acquired a bunch of the Microjet sprayers (the little water sprayers inside an aeroponic unit), some 3" and 6" net pots, and some bulkhead connectors (used for passing a pipe through the wall or floor of a container). We'd like to build a single-site aeroponic unit, specifically for larger plants, such as the eggplant. Although our eggplant has been a success, it's really been a bad neighbor to the other plants in the TurboGarden. I haven't found any other units to our liking, so we'll be building our own.

We've looked into a few types of materials. At the moment, we're leaning toward making some custom plexi-glass "lids" for some planters. One of the goals for this projects is to create an aeroponic unit with less expense than a commercially built unit.

This week we performed our first water change using the new Hydro-Logic Small Boy filter. All said, it worked out pretty well. Here are our quick observations on it:

It does filter chlorine and chloramine pretty quickly. It keeps equal output pressure as input pressure, but it does decrease your flow rate. We fill our hydro systems from a high grade (potable water) hose, which runs at standard household pressure. We've put the filter in-line with the hose. The filter uses 1/4" tube for it's inlets and outlets, which is a big reduction compared to the straight hose. Admittedly, it does decrease flow rate, but I'm unaware of anything that operates any faster. Secondarily, it's "fast enough" for our needs, so no harm done.

We really don't have any way to evaluate it's filtering effectiveness, as we don't have the special tools required. I'm considering taking a sample to a water place for a proper analysis.

Here's an odd item about the Small Boy filter: It includes a hose-thread to 1/4" tubing adapter. This adapter is very helpful, and we use it. The odd part is that they include only one... I built a second one from plumbing fittings at Home Depot.

We've hooked the filter up with a set of our quick connectors, and it's connected in-line with the fill line. The water comes from the tap, connects (optionally) to the filter, then to the hose. We can remove the filter from the chain at any time. Why remove the filter? Because we empty our tanks in the exact opposite of how we fill them... We use the pumps to pump the water "back out" the fill hose (and down the drain). We don't want the pump in place when dealing with waste water.

Things are moving slowly in the aeroponic TurboGarden. The eggplants are growing, but not as rapidly as before. We've added several more support strings to the eggplant, as the fruits are really weighing down the branches. I'm glad we have the large and sturdy lightstand.

We've picked our first strawberry, and lots more are forming. We're getting lots of flowers and lots of baby berries.